Diabetic Foot

Question 1

What does the term ‘diabetic foot complications’ refer to?

Answer 1

Encompasses the conditions of diabetic foot ulcer (i.e., a full-thickness epithelial defect below/distal to the ankle) and diabetic foot infections (i.e., any soft-tissue or bone infection occurring in the diabetic foot, including osteomyelitis).

Question 2

What are the risk factors for diabetic foot complications?

Answer 2

• History of diabetes mellitus
• Sensory neuropathy
• Previous history of foot ulcer
• Previous history of partial foot (toe) amputation
• Charcot’s mid-foot deformity
• Chronic kidney disease

Question 3

Briefly describe diabetic foot ulcers

Answer 3

A full-thickness epithelial defect that has been present for ≥2 weeks. Most occur in the forefoot, the portion of the foot distal to the tarsometatarsal (Lisfranc) joint.

Patients with Charcot’s arthropathy (mid-foot collapse) may develop ulcers in the mid-foot that are associated with structural abnormalities there.

Heel ulcers are often due to decubitus pressure in non-ambulatory patients debilitated by previous stroke.

Question 4

Whats signs and symptoms would indicate an infection in diabetic foot complications?

Answer 4

The presence of fever, chills, malaise, or anorexia is suggestive of an infection.

Question 5

How can a neuropathic and ischemic foot ulcer be differentiated?

Answer 5

• Neuropathic: warm, dry skin, foot pulses are palpable
• Ischemic: cool, pale foot with no palpable pulses

Question 6

What type of arthropathy is the best descrption of a Charcot joint?

Answer 6

Neuropathic

Question 7

What pulses should be assessed in diabetic foot complications?

Answer 7

• Dorsalid pedis
• Posterior tibial

Question 8

What investigations should be ordered for diabetic foot complciations?

Answer 8

• FBC
• Glucose level
• X-ray
• Microbial culture
• Doppler ultrasound
• Angiography

Question 9

Why investigate FBC? And what may this show?

Answer 9

• Ordered in all patients with diabetic foot complications. May suggest the presence of an infection; however, test has poor sensitivity.
• May show leukocytosis with left-shift.

Question 10

Why investigate blood glucose level? And what may this show?

Answer 10

• Ordered in all patients with diabetic foot complications. Often elevated in the presence of infection.
• May be elevated.

Question 11

Why investigate using x-ray? And what may this show?

Answer 11

• Ordered in all patients with diabetic foot complications to screen for osteomyelitis, fractures, joint stability, and other deformities.
• May show hypolucencies, cortical destruction/osteolysis and/or joint subluxation.

Question 12

Why investigate using microbial culture? And what may this show?

Answer 12

• If a diabetic foot infection is suspected, soft tissue or bone samples from the base of the wound can be sent for microbiological evaluation. If this is not possible, a deep swab can be taken as it may provide useful information on the choice of antibiotic treatment.
• Positive for causative organism in infection.

Question 13

Why investigate using doppler ultrasound? And what may this show?

Answer 13

• Used to assess the peripheral arterial
  circulation and determine the extent of vasculopathy
• Reduced peripheral arterial circulation

Question 14

Why investigate using angiography? And what may this show?

Answer 14

• Considered to be the best test for diagnosing peripheral artery disease.
• Haemodynamically significant (i.e., >50%) stenosis or occlusions between the aorta and the foot (if peripheral artery disease present).

Question 15

What organisms can commonly cause diabetic foot infections?

Answer 15

• Staphylococcus aureus
• Beta-hemolytic streptococci
• Pseudomonas aeruginosa

Question 16

Briefly describe the treatment for diabetic foot complications

Answer 16

• Wound care
• MDT care
• Offloading footwear
• Dietary advice and supplements
• Antibiotic therapy
• Drainage and/ or debridement

Question 17

When would oral antibiotic therapy be appropriate in mild diabetic ulcer infection? And what can commonly be prescribed?

Answer 17

• Mild infection defined as limited erythema ≤2 cm beyond the ulcer border and/or localised swelling, warmth or pain
• Treat with a suitable oral empirical antibiotic regimen→ flucloxacillin first-line

Question 18

When would oral or IV antibiotic therapy be appropriate in moderate diabetic ulcer infection? And what can commonly be prescribed?

Answer 18

• Moderate: defined as erythema >2 cm beyond the ulcer border or deep soft-tissue infection (e.g., abscess, osteomyelitis)
• Broad-spectrum, empirical antibiotics
  
  • Oral: clindamycin or trimethoprim/sulfamethoxazole plus either ciprofloxacin or amoxicillin/clavulanate
  • IV: vancomycin plus a carbapenem; ampicillin/sulbactam or a quinolone and metronidazole

Question 19

When would oral or IV antibiotic therapy be appropriate in severe diabetic ulcer infection? And what can commonly be prescribed?

Answer 19

• Severe: defined as a foot infection that is associated with two or more signs of the systemic inflammatory response syndrome(i.e., temperature >38°C; heart rate >90 bpm; respiratory rate >20 breaths/minute or PaCO₂ <32 mmHg; white blood cell count >12 × 10⁹ cells/L or <4 × 10⁹ cells/L)
• Broad-spectrum, empirical antibiotics:
  
  • Vancomycin plus one of three choices: a carbapenem; ampicillin/sulbactam or a quinolone and metronidazole

Question 20

What is the role of drainage and debridement in treating diabetic foot complications?

Answer 20

Surgery should be considered in moderate-to-severe infections to drain/debride any ongoing deep soft-tissue infection (e.g., drain an abscess or infected joint space, debride fasciitis/myonecrosis/necrotic bone).

Question 21

What is the role of amputation in treating diabetic foot ulcers?

Answer 21

• Minor amputations (i.e., toe or partial-foot resections) may be performed on areas with irreversible gangrene.
• Major amputations are generally reserved for two situations:
  
  • Infection or gangrene that is so extensive that reconstruction either is not possible or will not preserve meaningful function in the affected limb
  • Patients who have very little or no function in the limb

Question 22

What are the complications of diabetic foot complications?

Answer 22

• Delayed wound healing
• Osteomyelitis
• Charcot’s arthropathy

Question 23

What differentials should be considered in diabetic foot complications?

Answer 23

• Venous leg ulcer
• Gout
• Acute Charcot’s arthropathy

Question 24

How do diabetic foot complications and venous leg ulcer differ?

Answer 24

• Differentiating signs and symptoms: generally occurs in the gaiter area of the leg (i.e., below the knee, above the malleoli), and rarely occurs on the dorsum of the foot. May have surrounding lipodermatosclerosis (i.e., skin thickening and discoloration due to inflammation, scarring, and haemosiderin deposition).
• Differentiating investigations: ultrasound or venous plethysmography: can confirm venous incompetence, which makes this diagnosis more likely; however, venous leg ulcers can occasionally occur in the setting of a competent superficial venous system.

Question 25

How do diabetic foot complications and gout differ?

Answer 25

• Differentiating signs and symptoms: may be associated with pain, swelling, and erythema in the forefoot, but is not generally adjacent to a foot ulcer. May occur in the setting of previous history of gout.
• Differentiating investigations: plain x-ray of foot: shows radiographic signs of gout (i.e., joint space narrowing, scattered bony erosions, tophaceous arthritis).

Question 26

How do diabetic foot complications and acute Charcot’s arthropathy differ?

Answer 26

• Differentiating signs and symptoms: may cause pain, erythema, and swelling. May not be associated with a foot ulcer. Generally occurs in the midfoot (i.e., between proximal metatarsals to calcaneus).
• Differentiating investigations: magnetic resonance imaging of foot shows midfoot subchondral bone marrow edema (subcutaneous tissues are not typically involved).

Question 27

Briefly describe the monitoring of diabtic foot complications in type 1 diabetes

Answer 27

Feet checked by a primary healthcare professional at diagnosis and at least once a year thereafter, or sooner if any foot problems arise. They should also be advised to check their own feet on a daily basis.

Question 28

Briefly describe the monitoring of diabetic foot complications in type 2 diabetes

Answer 28

Feet checked by a primary healthcare professional at diagnosis and at least once a year thereafter, or sooner if any foot problems arise. They should also be advised to check their own feet on a daily basis.